1. Field of the Invention
The present invention relates in general to a flat-panel display device, and more particularly to improvements in a structural arrangement for and a process of sealing the device.
2. Discussion of Related Art
There are known flat-panel display devices such as a plasma display panel (PDP) and a field emission display (FED) arranged to display a desired image. Such a flat-panel display device includes a pair of flat panels at least one of which is transparent and which cooperate to define therein an air-tight space in which a gas discharge is induced to generate a ultraviolet radiation, or a cathode and a fluorescent layer are provided so that the cathode generates an electron beam that excites the fluorescent layer to generate light. The image is formed with the ultraviolet radiation or the light. An example of this type of flat-panel display device is disclosed in “Advanced Technologies of Displays”, p.82–84, 101–106, Chizuka Tani, first print, first edition, Kyouritsu Publishing Company, Japan, Dec. 28, 1998.
The flat-panel display device of the type described above is used alone to display a single image, or used as each of unitary components of a so-called “tiled display” device, which uses, as the unitary components, a plurality of the flat-panel display devices that are arranged adjacent to each other and cooperate to form a large-sized screen parallel to a direction of arrangement of the flat-panel display devices. The tiled display device is required to have a spacing pitch or spacing distance between effective display areas of the adjacent flat-panel display devices, which is as small as possible, in order to improve a high degree of continuity of an image and thereby enhance a quality of the image displayed.
In the tiled flat-panel display device known in the art, however, a sealing portion is provided along the periphery or perimeter of each flat-panel display device, so that a center-to-center spacing distance between the picture elements in the adjacent flat-panel display devices tends to be considerably larger than a center-to-center spacing distance between the adjacent picture elements within each flat-panel display device. Accordingly, the known tiled flat-panel display device is not capable of displaying an image with a high degree of continuity of the image. Where the flat-panel display device is not used as each unitary component of the tiled display device, but is used alone, too, the provision of the sealing peripheral portion causes a similar problem, since it is generally desired to maximize a ratio of the size of the effective display surface area of the display device with respect to its overall external size, while minimizing the dimension of the peripheral sealing portion.